Understanding and overcoming the threat of dysentery
Dysentery – its causes and consequences
Swine dysentery caused by Brachyspira hyodysenteriae is one of the most serious infectious diseases of the gastrointestinal tract, affecting the pigs throughout the post-weaning period and the fattening phases. Dysentery occurs worldwide in swine holdings of all sizes and causes high economic losses in affected farms.
B. hyodysenteriae is a gram-negative anaerobic spirochete which colonizes the large intestine. It is mainly transmitted through the feces of clinically sick animals and carrier animals. The infection with B. hyodysenteriae often remains latent, breaking out in periods of increased stress. Outbreaks are characterized by an epidemic spread, with a morbidity of 90% and a mortality of about 30-50%. The symptoms are similar to acute salmonellosis, Lawsonia intracellularis or parasites, i.e. severe haemorrhagic diarrhea. Serological methods like PCR or cell cultures are therefore necessary for a differential diagnosis.
Can Brachyspria be tackled
B. hyodysenteriae can survive for 90-120 days in latently infected pigs and for up to 8 months in the slurry, so that acute dysentery can occur periodically in infected holdings. A complete eradication of the bacterium is only possible, if all animals are removed from the barn and slaughtered. The slurry pit then needs to be emptied and disinfected with a compound which is effective against B. hyodysenteriae. If a complete eradication is not possible, e.g. in breeding herds, animals which show clinical symptoms need to be removed from the herd. Antibiotic treatment of the remaining animals is possible, however, to avoid antibiotic resistance, the concrete Brachyspira strain needs to be tested for resistance. High hygienic and management standards and pest control are vital to combat dysentery.
Additionally, the animals can be supported by preventing inflammatory processes in the digestive tract through functional feed additives. This can help to prevent the occurrence of dysentery and allow pig holders to reduce or remove feed antibiotics as well as reducing veterinary costs.